It's not anything about the theory itself (whether it's the right kind of theory), that distinguishes it. I think, at root, that is just an argument from authority.

The issue is that regardless of the dictionary definition, one usage of the word "theory" is basically equivalent to "random guess I just made up, have no evidence for, and have no way of testing." It may be an incorrect usage, but that doesn't change the fact that this confuses public discussion of anything which is actually a real, testable theory.

NetMasterOC3 wrote:

I'm having a hard time coming up with a case where you actually prove a negative proposition and not prove a positive proposition then logically negate it with an unprovable but well supported axiomatic condition.

I.e. If my task it to prove that I wasn't at a given location at a given time, I can only do so by proving that I was at another location at that time (a positive) and assert that axiomatically I can't be two places at once. However, so far as I know, I can't actually prove I can't be at two places at once, only assert that the overwhelming evidence we have supports that position.

Though I'm no expert in logic, so perhaps I'm completely wrong, but that's my understanding of what the phrase is trying to convey.

Well in some ways you're right, which is why I think the root of the phrase probably had to do with the ability to prove non-existence of things in the physical world.

But the phrase itself is so vague and inexact that it is often used in ways completely unrelated to that and incorrect. It is in fact possible to prove "a negative" in all kinds of circumstances related to math and logic. There's a whole class of formal proof for demonstrating that a certain thing can't exist, because if it does exist you arrive at a logical contradiction.

How bout this one? Plants always breathe in carbon dioxide and exhale oxygen.

I worked for a landscaping company once. We got into a discussion once about why the pallets of sod turned yellow if we didn't get them installed right away. I offered that it was because the grass was suffocating and that it wasn't getting enough oxygen (which I think is true though maybe its just lack of sunlight). Anyway, the boss thru a fit -- "plants breathe in carbon dioxide and breathe out oxygen you dummy" were his words to me if I remember correctly. Almost got me fired. Almost

Plants use the sugar created during photosynthesis and combine it with oxygen to provide energy for the plant cells. That process gives of CO2. Its just that the plants photosynthesis activity usually dwarfs its respiratory activity and results in a net production of oxygen. At night plants take up oxygen and give of CO2.

Regardless of the respiratory processes in play, a plant could "suffocate" just as well by lack of access to fresh CO2. Try growing a plant in a sealed container and see how well it goes.

A plant sealed in a glass container, assuming it gets light and water, will oxygen starve first. Plants need to respire constantly or they'll die at the cellular level.

Quote:

A related bit of trivia, I'm not sure that it rises to the level of "misconception": A large tree can weigh thousands of pounds. Where does all that mass come from?

(Hint: it's mostly carbon.)

Most people's first answer would be "the ground", but they'd be wrong.

crazydee wrote:

No it's not. It's mostly water, which does come from the ground.

But true for dry mass.

Notable exceptions are Epiphytes (air plants), which absorb H2O and CO2 from the air.It's wet mass is nearly ground free.

Lots of people in the US believe that medieval Europeans thought the world was flat and only with Columbus/Magellan and the age of exploration was that proved false. Well that's completely wrong. Any 12-year old schoolboy in the 8th-14th centuries would have told you the Earth was round. That was what all the astronomers/astrologers/cosmographers taught and wrote. It had to be round as it was at the center of the universe, which was composed of crystalline spheres (Aristotelian system).

Lots of people in the US believe that medieval Europeans thought the world was flat and only with Columbus/Magellan and the age of exploration was that proved false. Well that's completely wrong. Any 12-year old schoolboy in the 8th-14th centuries would have told you the Earth was round. That was what all the astronomers/astrologers/cosmographers taught and wrote. It had to be round as it was at the center of the universe, which was composed of crystalline spheres (Aristotelian system).

And what percentage of the population actually went to school?

Heck, Eratosthenes calculated (quite accurately) the circumference of the earth in the 200s BC (I don't remember exactly), if we go non-western it was done in India a couple centuries earlier than that. But good luck finding a lot of people who knew about it it back then. What was known in "scientific" circles and what was believed by the general public bore little resemblance back then (and now).

Lots of people in the US believe that medieval Europeans thought the world was flat and only with Columbus/Magellan and the age of exploration was that proved false. Well that's completely wrong. Any 12-year old schoolboy in the 8th-14th centuries would have told you the Earth was round. That was what all the astronomers/astrologers/cosmographers taught and wrote. It had to be round as it was at the center of the universe, which was composed of crystalline spheres (Aristotelian system).

And what percentage of the population actually went to school?

Heck, Eratosthenes calculated (quite accurately) the circumference of the earth in the 200s BC (I don't remember exactly), if we go non-western it was done in India a couple centuries earlier than that. But good luck finding a lot of people who knew about it it back then. What was known in "scientific" circles and what was believed by the general public bore little resemblance back then (and now).

Yes the schools were controlled by the Catholic Church, but official Catholic doctrine was that the Earth was round. Sure lots of people were uneducated, but we don't really know what they thought since they didn't write it down (for the most part). But even if only "educated" people knew the Earth was round that still invalidates the claim that Columbus/Magellan "discovered" the Earth was round.

Lots of people in the US believe that medieval Europeans thought the world was flat and only with Columbus/Magellan and the age of exploration was that proved false. Well that's completely wrong. Any 12-year old schoolboy in the 8th-14th centuries would have told you the Earth was round. That was what all the astronomers/astrologers/cosmographers taught and wrote. It had to be round as it was at the center of the universe, which was composed of crystalline spheres (Aristotelian system).

Not only that, but Columbus wasn't even trying to prove the fact, he was trying to take advantage of it to reach India the other way.

With Erastrothenes' results being forgotten, dogma at the time was that Earth's circumference was around 40% of its modern value, which would indeed have given Columbus a quicker way to India.

Eratosthenes' number wasn't forgotten though (well it was in the west for a time, but by Columbus' time it had been rediscovered). Both the Portuguese and the Spanish knew of Eratosthenes' estimate. The Portuguese rejected him because they calculated the correct distance to India, and recognized that it was much too far. The Spanish recognized the same thing, but for political reasons sponsored him anyway.

Columbus basically latched on to the most optimistic estimate he could find. His number was not the one widely accepted in circles of learning at the time, that was Eratosthenes'.

Lots of people in the US believe that medieval Europeans thought the world was flat and only with Columbus/Magellan and the age of exploration was that proved false. Well that's completely wrong. Any 12-year old schoolboy in the 8th-14th centuries would have told you the Earth was round. That was what all the astronomers/astrologers/cosmographers taught and wrote. It had to be round as it was at the center of the universe, which was composed of crystalline spheres (Aristotelian system).

And what percentage of the population actually went to school?

Heck, Eratosthenes calculated (quite accurately) the circumference of the earth in the 200s BC (I don't remember exactly), if we go non-western it was done in India a couple centuries earlier than that. But good luck finding a lot of people who knew about it it back then. What was known in "scientific" circles and what was believed by the general public bore little resemblance back then (and now).

Sailors would have known the Earth is round, or at least curved. Climb to the top of the mast on a sailing ship when approaching land. You will notice that the land "slides" over the horizon. You will also notice that the tops of high structures are visible first (eg churches). The same will happen when approaching other ships.

(Best time to see this is early morning in good visibility)

If the world was flat then you would see very tiny churches in the distance and see the bottom of the church at the same time as the steeple.

Sailors would have known the Earth is round, or at least curved. Climb to the top of the mast on a sailing ship when approaching land. You will notice that the land "slides" over the horizon. You will also notice that the tops of high structures are visible first (eg churches). The same will happen when approaching other ships.

(Best time to see this is early morning in good visibility)

If the world was flat then you would see very tiny churches in the distance and see the bottom of the church at the same time as the steeple.

What seems obvious to you and me was not always so obvious to people of other times and cultures. While it is true that the effect you describe was one of several reasons Aristotle used in deciding that the earth was a sphere, it shouldn't be taken as a given that lay people - or even educated people - will come to the same conclusions.

For example, in the middle ages, farmers plowing their fields would dig up spearheads and arrowheads and the like. When I see a rock that has been chipped away from all angles to form a point, I immediately think "tool." But what did they think? They didn't know what to think, so they went to the priests, who were supposedly the educated people of the day, and asked. The priest's conclusions? They were lightning bolts. Lightning had struck the ground, and the spearheads were what was left behind. This belief persisted well into columbus' day, and beyond. In uneducated people it even continued into the 19th century.

Maybe the captain, and the navigator if they weren't one in the same, knew it was round. Maybe he/they told the crew it was round too (and the crew most likely didn't believe them). But still, even if we grant that all educated people and all sailors and all people who worked at ports and lighthouses knew the world was round, that is still a small minority of the population.

Speaking of other cultures, how well was the shape of the Earth understood outside of Europe in the 15th century?

As for the OP:

According to a national survey commissioned by the California Academy of Sciences in 2008, only 53% of adults know how long it takes for the Earth to revolve around the Sun. And only 59% of adults know that the earliest humans and dinosaurs did not live at the same time.

Yes it is. I like to point people to it whenever they prattle on about how e.g. quantum physics "completely destroyed" Newtonian mechanics.

I run into people all the time who are just certain that there will soon be a breakthrough that will completely replace our understandings of physics, cosmology, etc., with something new - that everything we think we know will turn out to be "wrong." What they never seem to realize is that any new stuff has to not only be consistent with, but also explain, all previous observations - at least as well as the old stuff did. So F is still going to be equal to m times a for all ordinary purposes. I'm not expecting any of the three laws of TD to be overturned either; they have just plain worked too well for that to be likely.

Plants are grown inside the bottle with little or no exposure to the outside environment, and can be contained indefinitely inside the bottle if properly illuminated.

Almost any sealed biological system of this nature (with an energy source like light) will live, sometimes it's only blue-green algae and molds but the autotrophs and heterotrophs reach an equilibrium.

Plants are grown inside the bottle with little or no exposure to the outside environment, and can be contained indefinitely inside the bottle if properly illuminated.

Almost any sealed biological system of this nature (with an energy source like light) will live, sometimes it's only blue-green algae and molds but the autotrophs and heterotrophs reach an equilibrium.

So an acceptable equilibrium in gasses can be reached. Very nice. Here's a spot of mud to toss in the waters... can the light be provided via fluorescent bulbs in the room, or more unlikely, but more interesting to me at the moment, via fibre optic bundles from the outside running into an interior room?

Um, why not? Photons are photons; the plants don't care where they came from or how they were routed on the way. As long as there is enough energy at the wavelengths plants can use (and not so much energy that they cook) the plants will be happy.

Not all plants will work in a bottle garden. For example, plants which grow tubers or fruits will run out of CO2 for photosynthesis as they're storing their sugars (effectively sequestering carbon), and so run out of O2 for respiration.

Plants which just grow leaves and small flowers are best, as are smaller plants which have less requirements.

The point of a bottle garden is to conserve water, which they excel at.

A plant sealed in a glass container, assuming it gets light and water, will oxygen starve first. Plants need to respire constantly or they'll die at the cellular level.

Why so? It should be making plenty of oxygen from photosynthesis.

But it can't conduct photosynthesis without adequate CO2, can it?

Well actually yet it can - the oxygen producing reactions aka "light reactions" of photosynthesis don't require CO2. Typically most of the ATP and NADPH created by the light reactions thesis gets spent on the calvin cycle to fix CO2, but even without CO2, the light reactions continue to run, though slower.

Anyway, my point is that the first problem will occur when CO2 runs out (or low - since photorespiration will get painfully high as CO2 levels drop), and there won't be any lack of oxygen at that stage - thus it won't 'oxygen starve'.

If the world was flat then you would see very tiny churches in the distance and see the bottom of the church at the same time as the steeple.

I think there's a better explanation to be had. Aristotle provided physical and observational arguments supporting the idea of a spherical Earth: "The shadow of Earth on the Moon during a lunar eclipse is round." (De caelo, 297b31–298a10)